Differences between CPAP and BiPAP
CPAP (continuous positive airway pressure) is a form of treatment used to deal with patients suffering from breathing problems when they are asleep (sleep apnea). CPAP machines take positive pressure and then apply it inside the patients throat so as to prevent them from developing breathing complications when they are asleep. The airway pressure is usually delivered through an oxygen mask so as to maintain airway patency during sleep. This type of ventilation is mostly used for individuals suffering from acute respiratory failure (type one or two) and breathing problems when they are asleep. Patients who have been put under CPAP ventilation are usually monitored in the intensive care units, high dependency units and specialist respiratory units (Cosentini et al, 2010).
CPAP machines are commonly used to help patients with sleep apnea by delivering a stream of compressed air through the use of a nose mask, full-face mask and nasal pillow. Sleep apnea causes the upper airways of patients to become narrow as the patient is asleep which in turn reduces the oxygen levels in the blood. This reduction in oxygen causes arousal or sleep disturbance making it difficult for the patient to sleep properly. The CPAP machine keeps the airway open under air pressure to ensure that unobstructed breathing is possible therefore reducing the incidence of sleep apnea. The CPAP machine blows air at a prescribed pressure also known as titrated pressure which is air measured in centimetres of water (cm/H2O) at which most sleep apneas and hypopneas are therapeutically prevented (Tsuda et al, 2010).
BiPAP (Bi-level positive airway pressure) is another type of ventilation device that is used to deliver two types of pressure to patients who have breathing complications as a result of respiratory failure, strokes or heart attacks. BiPAP is considered to be an advancement of the CPAP ventilation technique since it provides more positive airway pressure at the end of inhalation and exhalation. BiPAP allows the setting of two different pressures to support the breathing activities of the patient and these pressures can be adjusted and set at separate rates (Kaplow & Hardin, 2007).
One of these pressures known as the inspiratory positive airway pressure (IPAP) is usually set as a high pressure to support the inhalation functions of the patient. The second type of BiPAP pressure known as the lower expiratory positive airway pressure (EPAP) is usually set at a low pressure to support the patient as they breathe out. The net effect of using the BiPAP machine is increased delivery of air into the patients lungs which means they will have less work trying to breathe. The pressure for the BiPAP machine is set at 5 to 10 cm H2O titrated pressure to ensure that there is airflow in the patients lungs (Kaplow & Hardin, 2007)
There are various modes or approaches that are used to supply titrated pressure to the patients lungs and they include the spontaneous mode, the timed mode and the spontaneous/timed mode. The spontaneous mode triggers spontaneously the inspiratory positive airway pressure (IPAP) in the device that is being used to deliver the titrated pressure which in turn converts it into the positive airway pressure (EPAP). The second mode used for the BiPAP is the timed mode where the IPAP and EPAP cycling is triggered by a machine at a set rate which is usually expressed in breaths per minute (BPM). The spontaneous/timed mode device triggers IPAP on patient inspiratory effort and there also exists a backup rate that is set to ensure that patients still receive a minimum number of breaths per minute in the event they fail to breath spontaneously (Rueda, 2009).
One difference between the CPAP and BiPAP ventilation devices is that the CPAP delivers a single predetermined amount of pressure while BiPAP has two forms of titrated pressure to help the patient breath. As mentioned earlier a prescribed pressure known as the titrated pressure is usually given to patients under the continued positive airway pressure (CPAP) while the BiPAP pressure devices utilize two levels of pressure known as the inspiratory positive airway pressure (IPAP) and the lower expiratory positive airway pressure (EPAP). The devices that are used in helping patients to breathe in the CPAP technique apply a continuous pressure to the patients airways while the Bi-level positive airway pressure (BiPAP) devices exert high pressure when patients breathe in and deliver low pressure when they breathe out. This basically means that BiPAP devices lower the pressure of air that has been breathed out and they increase pressure in the air when the patient breathers in. This increase and reduction in pressure is not possible in the CPAP ventilation devices aimed at reducing cases of apneas and hypopneas (Cooper et al, 2006).
The CPAP devices also differ from BiPAP in that patients using the machines have to use a lot of force when exhaling to work their lungs against the extra pressure. This is mostly attributed to the single level of pressure that is used by CPAP devices to help patients during respiratory exercises. This proves to be a tiring exercise for the patients especially those that are suffering from neuromuscular diseases. The BiPAP devices on the other hand are able to adjust air pressure which means that they easy to handle and they can be adapted to suit the breathing needs of patients. The dual pressure adjustments that come with the machines help patients to get more air in and out of their lungs without much effort (Collen, 2009).
Arterial Cannulation
Arterial cannulation is a procedure that is commonly performed in the healthcare management of patients who are critically ill. The procedure involves the use of arterial catheters to allow for the continuous monitoring of the patients blood pressure. These procedures are usually used for patients who are suffering from heart disease, coronary artery disorders and other heart disorders that affect the proper flow of blood. Arterial catheters have been considered to be relatively safe with a low incidence of serious complications to the patients who use this mode of treatment. The main arteries that are used for cannulation or catheterization include the radial arteries, ulnar, brachial, femoral and axillary arteries with the radial artery being the most commonly used artery for cannulation amongst children and adults (Barash et al, 2009).
The radial artery is common because of the superficial nature of the vessel and the ease of maintaining the site of the artery as well as the arteries accessibility and presence of a collateral supply of blood. Multiple arteries can be used for the direct measurement of blood pressure where an Allen test is performed by compressing both the radial and ulnar arteries of the patient. The Allen test can be used to identify the potential sites for arterial catheterization since it requires the patient to tighten their fists as they compress both the radial and ulnar arteries of the patient. The release of pressure on each artery determines the dominant vessel that is used to supply blood to the patients hand. This vessel is then used for the arterial cannulation as long as the patient responds positively to the Allen test (Barash et al, 2009).
Many cannulation sites have been used for the direct arterial blood pressure monitoring of patients with heart problems. A necessary condition which is needed before any arterial cannulation techniques are conducted is the identification of the arterial pulse on the patient which is usually enhanced by using the Doppler flow detection device. Other techniques that can be used in the identification of potential sites for arterial cannulation include the transfixion-withdrawal method, the direct arterial puncture method and the guide wire-assisted cannulation technique which is also referred to as the Seldinger approach. Identification of potential sites for arterial cannulation is an important activity as it helps to determine the arterial pulse of the patient and whether they can be able to withstand the cannulation procedure which is usually invasive in nature (Yavuz, 2008).
The post insertion management of the arterial catheter involves activities that are directed towards managing the potential complications which might arise when a catheter is introduced into the patients body. Arterial catheters in general are associated with a variety of complications some of which include the infection of the patients blood stream, damage to the arteries during the insertion of the catheter, reduction of blood flow to the various tissues in the insertion site and hemorrhaging as a result of a ruptured artery (ICCMU, 2007).
For post insertion management activities to be conducted effectively, the type of dressing used to put in place the arterial catheter should be transparent and occlusive. This will enable the health care workers responsible for the arterial cannulation to assess the arterial catheter site for any infections and also ensure that the catheter is safe and secure. The catheters also need to be checked at an hourly basis after they have been inserted to ensure that they are performing their intended purpose. Checking the catheters hourly also ensures that there is no room for infections or other harmful bacteria to grow in the cannulation site. Infections can be prevented through the use of closed pressure transducer sets where it is possible for the patient to develop an iatrogenic anaemia or clinician infection. There also needs to be a frequent assessment of the insertion site so that any movement of the catheter can be easily detected (ICCMU, 2007).
The most common technique that is used to detect the normal waveform of the patient is the Allen test which seeks to evaluate the collateral circulation of blood to the hand via the ulnar artery. The hand is usually elevated and made into a fist for 30 seconds to allow for simultaneous pressure to the ulnar and radial arteries of the patient. The patient is then told to open their fist and if colour returns to the hand in five seconds, the Allen test is negative meaning that the radial artery can be cannulated. If on the other hand colour does not return to the hand within five seconds, the Allen test is positive or abnormal meaning that the patients blood supply to the hand is insufficient to support an arterial cannulation procedure (Asif & Sarkar, 2007).
Extra or external ventricular monitoring and drainage systems are those that are used to monitor and drain cerebrospinal fluid from the brain and spinal cord of a person recorded to have a high intracranial pressure. Extra ventricular monitoring and drainage activities are the standard health care activities that are used to temporarily control intracranial pressure by draining the cerebrospinal fluid externally from a patients body (Cartwright & Wallace, 2007). EVDs and intracranial pressure (ICP) monitors are the most commonly used tools in the neurological management of patients suffering from brain tumours and other neurological disorders. Apart from draining the infected cerebrospinal fluid (CSF), extra ventricular drainage systems are also used in neuro critical care situations such as those that relieve elevated intracranial pressure (ICP), those that drain bloody CSF or blood haemorrhaging and those that monitor the flow rate of cerebrospinal fluid (Ehtisham et al, 2009).
The role of extra ventricular monitoring and drainage as a therapeutic intervention to the management of intracranial pressure is to lower this pressure through the employment of intermittent techniques that will continuously drain the cerebrospinal fluid from the brain and spinal cord of the patient. EVDs also facilitate the measuring of the intracranial pressure of the patient on a temporary basis after the patient has been prescribed with intrathecal medication. The equipment that is used to monitor and drain CSF from the patients brain and spinal cord includes an EVD with pressure tubing that is connected to a monitor and drainage system, a measuring tape that has been marked in centimetres and a carpenters spirit level. A doctors order is also needed for the CSF drainage to take place where the doctor prescribes the level of ICP that will be used to initiate the drainage (AACCN, 2009).
Monitoring and draining the intracranial pressure of an individual is an important activity because the build up of this type of pressure leads to the distortion and dysfunction of a persons brain nerve pathways. In severe cases the build up of intracranial pressure in the brain and spinal cord of an individual leads to herniation which is the pathological displacement of brain tissue. If the ICP level is close to the mean arterial blood pressure of an individual, it might lead to an impairment of cerebral blood flow of the patient which leads to brain dead cells and the eventual death of the patient (Dixon, 2009).
The monitoring and drainage of CSF is therefore an important activity as it reduces the probability of brain swelling, intracranial mass lesions or obstructions in the brain and spine that complicate the movement of cerebrospinal fluid. EVD systems are used for the therapeutic drainage and monitoring of CSF thereby reducing the build up of intracranial pressure (Dixon, 2009). While they are important in alleviating brain problems, EVD systems give rise to complications such as brain infections, brain leaks as a result of the incorrect height of the drainage burette and the inaccurate monitoring of intracranial pressure (AACCN, 2009).
Therapeutic Hypothermia
Therapeutic hypothermia is a form of medical treatment used to treat patients who have suffered from ischemic injuries such as brain injuries, strokes, spinal cord injuries and neurogenic fever as a result of poor blood flow by lowering their body temperature. Therapeutic hypothermia can be administered through invasive procedures such as the femoral catheter which is used to regulate the patients body temperature and the non-invasive procedures such as chilled water blankets and leg wraps that have been put in direct contact of the patient. It is usually recommended to initiate therapeutic hypothermia treatments as soon as individuals or patients suffer from possible ischemic injuries because time moderates the effectiveness of hypothermia as a neuroprotectant (Jess et al, 2009).
Past research has revealed that hypothermia possesses neuroprotective qualities that decrease cerebral oxygen when a patient is suffering from an ischemic injury. Recent studies have been able to reveal that prolonged moderate hypothermia at 32 to 33 degrees Celsius that has been maintained for a period of between 12 to 24 hours in a comatose patient usually leads to an improvement in the neurological outcome of the patient. These studies were also able to reveal that the patients experienced a reduction in their neurological injuries which were cooled down by the therapeutic hypothermia. This reduction was mostly attributed to a decrease in the free radicals that were normally generated after reperfusion. These radicals usually overwhelmed the enzymatic and non-enzymatic neuronal protective mechanisms of the body leading to the destruction of neural pathways in the brain (Birch, 2005).
The introduction of moderate therapeutic hypothermia after patients have suffered from ischemic injuries has been successfully used since the 1950s. This mode of treatment showed improved neurological recovery in patients that had suffered heart attacks, strokes, cardiac arrests and other forms of ischemic injuries. Therapeutic hypothermia was able to reduce injuries to the neural networks of patients caused by oxidative stress resulting from the restoration of blood supply to respond to the ischemic injuries. Hypothermia that was therapeutically managed was also able to moderate the intracranial pressure in the brain or spinal cord of an individual thereby minimizing the harmful effects of a persons immune inflammatory system during periods of reperfusion (Birch, 2005).
The techniques that are used to conduct therapeutic hypothermia include invasive and non-invasive techniques. Cooling catheters which are a type of invasive technique are usually inserted in the femoral vein of an individual and a cooled saline solution is then circulated within the patients body lowering their temperature. The non-invasive techniques require the use of water blankets or leg wraps that have been placed in direct contact with the patients skin so that they can lower their body temperature to the appropriate level. These non-invasive techniques lower the body temperatures of ischemic injury patients where 70 percent of their bodies are covered with these treatments (Hinz, 2007).
Principles of Cardiac Defibrillation
Cardiac defibrillation is a common treatment that is used in life threatening situations that include cardiac arrhythmias and pulse-less ventricular veins where the patient fails to record a pulse in their major blood arteries. Patients who suffer from heart failure or severe strokes are usually at a high risk of sudden cardiac death due to heart failure progression. Cardiac defibrillation involves delivering an electrical charge to the affected patient so as to initiate the patients cardiac functions in the event of cardiac arrest. This device usually depolarizes the critical mass of the patients heart muscle thereby terminating a case of cardiac arrhythmiasis. This in turn caters for a normal sinus rhythm that is sustained by the bodys natural pacemaker ensuring the flow of blood in the heart. Defibrillators are external devices but they can be implanted in a patient depending on the type of device that is used for the cardiac defibrillation exercise (Trayanova, 2006).
The principle of cardiac defibrillation is mostly dependent on the position of electrodes used to depolarize the critical mass of the heart muscles. These electrodes are usually delivered by a variety of components that make up the cardiac defibrillators and one of these components is the capacitor. A capacitor is made up of a pair of conductors that are used to deliver electrodes to the heart. These conductors lose and gain electrons quickly thereby maintaining a continuous flow of electric currents that are charged to deliver electrodes. The electrodes are able to store and deliver a large amount of energy stored as electrical charges to the patient initiating their cardiac functions (Trayanova, 2006).
Inductors are also important components of cardiac defibrillators because they successfully deliver the current to the heart by prolonging the duration of current flow. They can accomplish this because of their ability to produce a magnetic field that will allow the flow of electrical charges to facilitate the shocking of the patient. As soon as the current passes through the inductor, it generates a flow of electricity in the opposite direction of the charges which is used to oppose the current flow (Hayes & Friedman, 2008). The two types of defibrillators that are commonly used in the therapeutic shock of patients who have suffered ischemic injuries include the monophasic and biphasic defibrillators. The biphasic defibrillators were introduced recently into the medical market but before then the monophasic defibrillators were commonly used to depolarize the patients heart muscles. The advances in technology saw the biphasic defibrillators being developed to meet the treatment needs of life threatening disorders such as cardiac arrhythmias (Paradis et al, 2007).
Monophasic defibrillators differ from the biphasic defibrillators in that they deliver the current flow in one direction while the biphasic defibrillators deliver the current in two directions which means that they have a higher efficacy rate compared to the monophasic defibrillators. In the monophasic defibrillator, the current moves from one paddle to another while in the biphasic unit the flow moves in two directions which are from one metal paddle to another and then again in reverse to initiate the flow of the electrical current. The multiple direction of the current flow supported by the biphasic defibrillators has been able to lower the threshold for successful defibrillation thereby saving more lives when compared to the monophasic defibrillators (Paradis et al, 2007).
Research work that has been conducted on the efficacy of the two defibrillators has been able to reveal that the biphasic unit has a higher efficacy rate when compared to the monophasic defibrillator. This can mostly be attributed to the 90 percent shock rate that the biphasic defibrillators possess in reviving patients against the 75 percent shock rate of the monophasic defibrillator. In defibrillation dosing, the defibrillator units need to deliver an appropriate amount of electrical shock to ensure that the heart is charged at an appropriate current. In the monophasic units, the delivery of the treatment dosage usually takes a great deal of time when compared to the biphasic units. Less energy is also needed to deliver the current flows to the patients chest for the biphasic unit which is not the case for the monophasic units that require more energy to apply the currents (Gregory & Mursell, 2010).
A waveform for a defibrillator is important because it delivers the changing patterns of the current when a patient is being shocked. The waveforms between the two defibrillators are different in that the biphasic units are able to adjust the waveforms to ensure that the current flow is able to move through the heart thereby resuscitating the patient. The American Heart Association considers the biphasic units to be the safer and effective alternative to cardiac support treatments because they provide efficient and personalized waveforms used to revive cardiac arrest patients (Gregory & Mursell, 2010).
The clinical application of cardiac defibrillation involves placing a metal paddle with an insulated plastic handle on the patients skin after the application of a gel. The purpose of the gel is to reduce the electrical resistance that will be caused by the flow of electrical charges on the patients body. The paddles which are also known as resuscitation paddles are usually placed on the patient according to two schemes one of which is the anterior-posterior scheme. This scheme involves placing one resuscitation electrode over the lower part of the patients chest and placing the other behind the heart. The second scheme referred to as the anterior-apex scheme places anterior electrodes in the right side of the patients body while the apex electrode is usually positioned on the left side of the body. The application of these schemes requires health workers such as nurses to consider the severity of the patients cardiac arrhythmias so as to determine the amount of current flow that will be applied to the patients chest (Hayes & Friedman, 2008).
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